1. Field of the Invention
The present invention relates to the field of computers. More particularly, this invention relates to a power distribution system and a method for distributing power regulating components throughout a computer system in order to lessen heat dissipation within a main computer casing.
2. Art Related to the Present Invention
Over the last decade, there have been many advances in semiconductor technology, semiconductor packaging and miniaturization. One result of these advances is the development of higher performance semiconductor devices defined as integrated circuits having additional and/or enhanced features (e.g., operating at greater frequencies) than prior semiconductor devices. These higher performance semiconductor devices have enabled computer manufacturers to build and design faster and more sophisticated computer systems and to integrate more features into a computer casing. However, a number of disadvantages have arisen with respect to the use of these higher performance semiconductor devices.
A paramount disadvantage is that such additional features and performance typically cause greater power consumption and heat dissipation as a by-product than prior computer designs with fewer integrated features. A second disadvantage associated with the sophisticated computer systems is that more heat is being dissipated by a number of power regulating components within the computer casing because they are supporting a larger range of requisite power levels. Finally, as a trend, the computer market is expecting and valuing smaller computer casings thereby driving computer designers (especially portable computer designers) to design power systems closer to a thermal limit of the smaller casing by integrating more features therein.
Referring to FIG. 1, a conventional power distribution system for a typical portable computer 1 is illustrated. The portable computer 1 comprises a main computer casing 2 for protecting inner circuitry of the portable computer 1 from damage and providing a mobile, convenient enclosure for carrying by hand or in one's briefcase. Such inner circuitry within the main computer casing 2 includes the improved semiconductor devices such as a processor, memory element, etc. (i.e., "core components") 3, modules such as hard disk, floppy disk drive and cursor control devices, as well as power regulating components. The portable computer 1 further comprises a display casing 4 including display hardware 5 (e.g., a backlight) operating in conjunction with a display screen 6, such as a liquid crystal display ("LCD").
Optionally, a conventional single line alternating current-to-direct current ("AC-to-DC) power adapter (the "adapter") 7 may be coupled via an adapter cable 13 to a power connector 8 of the main computer casing 2 so that the adapter 7 typically operates as a primary power source of unregulated DC power flowing into a motherboard switching regulator 9 of the portable computer 1. The motherboard switching regulator 9 is a major power regulating component for the core components 3 within the main computer casing 2 as well as for display hardware 5 and display screen 6 within the display casing 4. Unregulated DC power is likely supplied to the motherboard switching regulator 9 by the adapter 7 or a battery source 12.
Besides the motherboard switching regulator 9, a plurality of auxiliary power regulators are commonly used within the main computer casing 2 to regulate power. For example, multiple linear regulators 10 may be implemented within the main computer casing 2 in order to supply power outputs at a variety of different voltages or ripple requirements. Additionally, a charging regulator 11 may be implemented for regulating a power output to charge the battery source 12. The charging regulator 11 is required to properly charge the battery source 12 to some consistent voltage or current, while losses of power within the adapter cable 13 and fluctuating power demands of the computer through the motherboard switching regulator 9 work to undermine any consistency of power being delivered to the charging regulator 11. In this conventional power dissipation circuit, heat is generated by the core components 3, motherboard switching regulator 9, linear regulators 10 and the charging regulator 11 within the main computer casing 2.
A critical problem that exists in this conventional power distribution system is that the integration of higher performance processors and more features (i.e., brighter screens, more peripheral input/output ("I/O") support) into a smaller main computer casing causes greater amounts of heat to be dissipated within the smaller main computer casing 2 (i.e., a greater heat density). As a result, the overall temperature within the main computer casing 2 is drastically approaching or has arisen to a calculable boundary temperature known to adversely affect the reliability of the core and power regulating components within the main computer casing 2. In addition, due to the fact that heat is typically dissipated through the main computer casing 2 of portable computers, these machines may become more uncomfortable to work with when placed on the user's lap.
For conventional personal desktop computers solely receiving power from an AC outlet, heat can be adequately dissipated by implementing a fan element to exhaust heat from an interior of the main computer casing. However, for portable computers which may be operating in public environments and generally under battery power, this fan element would add audible noise and consumes additional battery power, which are crucial disadvantages in a competitive portable computer market.
Another problem is that the computer market places a high premium on smaller computer casings, causing portable computer designers to drive more features and create a greater heat density within the smaller main computer casing.
Another critical problem is that the conventional power distribution system can be less efficient as evidenced by the above-mentioned thermal dissipation problems and by not employing sufficient flexibility in power modes and switches to disable power to idle circuitry. As a result, such inefficiency indicates that power provided by the battery source is being needlessly wasted, reducing its run-life.
Yet another problem is that there does not exist an AC-to-DC adapter generating two adapter power outputs of which one of the adapter power outputs is dedicated to charging batteries within the computer system while the other adapter power output normally supplies power to the computer circuitry to run the computer system.
Hence, it is desirous to create a power distribution system which mitigates thermal dissipation within the main computer casing but still supports an hierarchical application of power ("power mode hierarchy") designed to first supply power to the most critical components. As a result, the higher performance semiconductor devices and adequate number of integrated electronic features could be implemented within a smaller main computer casing without causing excessive heat and reliability problems.